Mobile swinging lift platform equipment



Jan. 22, 1957 M. E. MITCHELL MOBILE swINGING LIFT PLATFORM EQUIPMENT Filed Aug. 15, 1952 3 Sheets-Sheet 1 M m E N .Il m f m .m ,M mK un 2 M YM B I. I MUIMUFEIlIILiIIIQMMMI mi u W \IQ% \Q% m \v\ WN &\ M MMM MN bm wm L v T II .ht IiI I I ...'.WUIIIIIHI .v Qs Mx I\ wus wm Jan. 22, 1957 M. E. MITCHELL 2,778,694

MOBILE SWINGING LIFT PLATFORM EQUIPMENT Filed Aug. l5, 1952 3 Sheets-Sheet 2 ff INI'ENTOR.

MAURICE E, MITCHELL,

Jan. 22, 1957 M. E. MITCHELL MOBILE 'SWINGING LIFT PLATFORM EQUIPMENT Filed Aug. l5, 1952 3 Sheets-Sheet I5 INVENTOR. I Maumee IMWCHELL,

United States Patent O MOBILE SWINGING LIFT PLATFORM EQUIPMENT Application August 15, 1952, Serial No. 304,588 2 Claims. (Cl. 304-29) This invention relates to equipment for servicing elevated objects, such as mast arms of utility poles, bridge ceilings, elevated wires and supports and cables, and the like; and to the combination of such equipment with a mobile truck.

Servicing such elevated objects, as by painting, is tedious and time-consuming, and involves a high labor cost. ln the case of many elevated objects, such as is usually the situation with the particular examples mentioned above, such objects are either not suciently rigid to support a ladder or there is no abutment against which the upper end of a ladder may rest. Even where such support is available, it is usually impractical to erect any scaffold-like structure having a work-platform of any appreciable horizontal extent, and much of the servicemans time and effort is wasted in setting up the equipment used and moving it to successive portions of the elevated object or to successive objects which are to be serviced. The disadvantages are exemplified by the widely used practice of taking down mast arms for painting. The usualV result is that proper servicing is wholly omitted or left undone for extended periods.

it is an object of my invention to provide self-supported means for service access to elevated objects. Another object is to provide such means in combination with a mobile vehicle. A further object is to provide a service platform which will have in its operative position considerable horizontal extent transversely of the Vcarrying vehicle, yet which is retractable to an out-of-the-way position substantially within a vertical projection of the vehicle itself. A further object is to provide such means which are readily adaptable to differing applications and requirements of height.

These and other objects will become apparent from the following description.

In accordance with the preferred form of my invention l provide a pair of horizontal platforms mounted on interrelated column-like members supported vertically on opposite sides of a truck. These columns are extensible, as in synchronism, and means are desirably provided to rotate each supported platform through 90 during a portion of its vertical movement. In the retracted low position of the platforms, they lie longitudinally of the truck and substantially within the vertically-projected area of the truck. As they are elevated, and desirably during the rst or lower portion of their elevation, they are swung horizontally through 90 so that the two platforms move to a cooperative end-to-end position to provide an elevated, substantially continuous walkway extending-transversely of the truck and projecting considerable distances beyond the sides of the truck. Thus I provide a service walkway extending transversely across and beyond the sides of the truck, which can be raised or lowered through a considerable range of adjustment, and which when completely loweredrnoves to a low and retracted position permitting the truck to be moved readily from place to place'. Power driven mechanism for elevating and lowering the platform is carried by the truck.

2,718,694 Patented Jan. 2.2, 1957 Frice For accessibility to the platforms, I provide ladders carried thereby or by the columns and extensible therewith. Guardrails are preferably mountedoneach platform and desirably are swingable between a latched, operative, upward position, and a retracted storage position.

The extensible columns may have one or more stages of extension. Desirably, the columns are interconnected and braced one from the other and the elevating means is such that both platforms rise and lower in unison, but the two platforms may be independently operable, as for service work in which only one platform is required.

Ground-engaging stabilizing struts may be mounted on the truck if desired.

The accompanying drawings illustrate the invention.

In the drawings:

Fig. 1 is a rear elevation of a truck equipped with a preferred form of platform apparatus, and including singlestage elevating mechanism. The solid lines show the platforms, rails, and ladders in an elevated and extended position, and the dotted lines show such parts in retracted position;

Fig. 2 is a side elevation of the equipment shown in Fig. l, with the platforms shown in solid lines in retracted position and in dotted lines in elevated position;

' Fig. 3 is a plan view of the apparatus shown in Fig. 2;

Fig. 4 is an end elevation of a platform showing in solid lines the guardrail in operative or upward position, and in dottedlines its folded-down or retracted position;

Fig. 5 is a fragmental detail taken on the line 5-5 of Fig. 4 showing latch means for holding the handrail in upright position;

Fig. 6 is a horizontal section taken on the line 6-6 of Fig. 7;

Fig. 7 is a side elevation of the platform-supporting columncarried at the right side of the truck shown in Fig. l, showing the parts in retracted position;

Fig. 8 is a fragmental developed view showing a camfollower arrangement which is preferably employed in the lift mechanism.

Fig. 9 is a horizontal section taken on the line 9 9 of Fig. l0;

Fig. l() is a view similar to Fig. 7, showing a modified lift column having a two stage lift. y

In the single-stage lift apparatus shown in Figs. 1 7, a panel truck 1t) is provided with a pair of slotted sleeves or tubes 12 rigidly attached to the truck and disposed vertically at opposite sides of the truck at points between the door openings and the rear fenders. These tubes 12 extend from the bottom of the truck body upward to a point above the truck body; their actual over-all length being dependent upon the elevation capacity desired and the minimum over-all height desired for clearance purposes. The two tubes l2 are symmetrical, as generally are the other elements of the platform and lift apparatus, each member of the apparatus at the right side of the truck having a counterpart at the left-side of the truck.

Telescoping within each tube 12 and upwardly extendable therefrom is a platform-supporting post or rod 14, on the top of which is firmly supported a horizontal, long narrow work platform 16. Each platform is a rigid unit, comprising suitable beams l and an overlying lloor. As is shown in Fig. 3, the platform 16 is desirably not geometrically centered over the axis of the post 14 and sleeve 12, but instead, the post is at that side of the platform which lies outermost when the platform is in lowered position, and at a point spaced from one end of theplatform substantially equal to one-'half the distance between the right-hand and left-hand supporting rods 14.

With each platform so supported, the lowered position of the platforms disposes themsubstantiallywholly within the* vertically projected area of the truck, vwhich condi` tion is desirable for road travel. Each platform extends forward from the supporting post 14 a considerable distance, and as the platforms are raised, their forward ends; swing horizontally outward of the truck to provide anextended walk-Way extending transversely of the truck and well beyond its sides. The sho-rter ends of the platforms, which in retracted position lie rearwardly of the supporting post 14 swing inwardly over the truck to a position in which they substantially meet. The two platforms then cooperate to provide a substantially continuous walkway extending transversely above the truck. To provide clearance during the inward swinging movement of the platforms, the inner rear corner of each platforrnis rounded off on a radius about the axis of the rods 14,.as indicated at 2d.

For elevating the platforms between their lovvermost retracted position and their elevated work positions, lift means is provided to rotate and extend the posts 14 with respect to the tubes 12. As shown, the lift means is cable operated. A pulley 28 is mounted on a horizontal axis on a collar 3?. secured to the top of each vertical tube 12, and a cable passing over such pulley 2@ has one end operatively connected to a powered windlass (not shown) carried by the truck, and the other end 44 is attached to an eye-bolt i5 which is connected to a stud 48 projecting laterally and outwardly from the lower end of the post 14, through a guide slot SZ cut in the tube 12.

When the platforms are to operate in unison, both the right and left cables 36 are connected to the same windlass drum orto interconnected drums.

The slot 52 in each tube 12 extends substantially the full height of the tube, and except at the very bottom, each slot is straight and parallel with the axis of the extensible supporting column 12--14- The slot 52 and the stud 48 are so related to the angular position of the platform that when the stud is in the straight portion of the slot the platform lies in its transverse position with respect to the truck. To provide the 90 horizontal swinging of the platform, l form the lowermost portion of the guide slot 52 as a cam 56 extending 90 around the tube 12 over a distance of about 18 inches at the bottom of the tube 12. The stud d8 may be considered to be a cam follower so that its vertical movement through the cam portion S6 of the slot 52 causes the post 1f@ and platform 16 to swing through 90 from the longitudinal retracted position of the platform 16 to the transverse position thereof. The cam portions 56 in the two tubes 12 at opposite sides of the truck are symmetrical but of opposite hand, so that both platforms swing forward in retracted position.

Since the cam portion 56 of each slot is at the bottom thereof, the swinging movement of the platforms will occur during the first movement thereof from their fully retracted positions. The platforms thus move immediately to the cooperating transverse positions in which they form a substantially continuous walkway, and such walkway can be lifted as such to any desired elevation and held therein for use.

Instead of using the stud 43 itself as a cam follower', separate cam-following rollers are desirably provided. AAs Shown in Fig. 8, the stud d@ is rectangular in section, and a pair of cam-following rollers t9 are mounted on the post 14 immediately above that stud 4S and positioned respectively to engage the opposite sides of the slot 52 and of its cam portion S6.

To provide access to the walkway, two ladders or ladder sections are associated with each lift column 12-,14. A lower ladder 13 is fixed to each lower section or tube 12 of each lift column, preferably in a position ati against the truck and at the rearward side of the tube 1-2. An upper ladder 60 is fixed to, and hence swingable and elevatable with, the platform 16. The ladder 60,is. connected at the top to the platform itself, and at thebottom to the stud 48. When the platform is in retracted` position, the ladder lies ahead of the sleeve 12 and dat against the truck-side. As the platform swings outwardly the ladder 60 moves with it, to a position in a vertical plane at 90 to the plane of the stations ry ladder 13, where the serviceman can conveniently use the ladders 13 and 6) in series to climb from the ground to the work platform. The connection of the lower end ofthe ladder 60 to the stud 48 serves to brace each from the other.

Each platform 16 is desirably provided with a guardrail 56 along at least one long side, and the guardrails desirably fold down when the platforms are in retracted position. The handrails shown are supported on L- shaped posts (see Fig. 4) having a horizontal bottom leg 70 and an upright leg 72. The free ends of the bottom legs .753 of the L-posts 7 0 7 2 on each platform are pivoted 'i aiigned bearings 74 at the ends of the platform, at p nts slightly offset from the mid points of those ends. in raised operative position of each handrail, as shown in solid lines in Fig. 4, it is desirably locked at at least one end by a spring-pressed latch 76 mounted on the platform 16 and engaging a keeper '78 secured to the horizontal bottom leg 70. Upon release of the latch 76 as by its knob S0, the handrail and its supports can be pivoted about the common axis of its bearings 74 through 180 to the retracted position shown in dotted lines in Figs. l and The Vertical legs 72 of the supports then lie in a depending position, clearing the side of the platform, and positioning the rail below the outer side of the retracted platform.

Desirably, the elevating apparatus and platforms on opposite sides of the truck are tied together and braced from each other. As shown in Figs. 1-3, the two tubes 12 are interconnected at their tops by two spaced tie rods 82 extending transversely across the truck top, and the two posts are interconnected by a tie rod 84 connected at its ends to sleeves 86 which rotatably receive the platform-supporting posts 14.

Where greater elevation capacity is desired than can conveniently be obtained with the single-stage lift apparatus shown in Figs. l-7, multi-stage lift means may be used, such as that shown in Figs. 9 and l0. The multistage lift shown, like that of Figs. l to 7, comprises a xed tube 112 having a slot 152 with a lower cam portion 15o, and supporting a pulley 128 on a collar 132 at the top. A cable 136 extending over the pulley is operatively connected at one end to a windlass and at the other end to a stud 14S projecting through the cam slot in the fixed sleeve 112. ln this case, the stud 14S is fixed to an intermediate lift tube 171 -telescopically received in the fixed tube 112. A top lift post 175 is telescopically received within the `intermediate tube 171 and platform 116 is mounted on the upper end of the post 175. This inner post 175 is provided with a longitudinally extending groove 177 parallel with the axis of the rod, to receive secondary lift cable or chain 179. The secondary cable is fastened to the bottom of the top lift post 175, and extends upward `in the groove 177, over pulley 133 carried by the top of the intermediate lift tube, and then downward outside the lift assembly to a fixed bracket on the fixed tube 112. So far as lift motion alone is involved, the bracket 185 could be at any point on the tube 112, but to allow for the desired 90 rotation of the two upper lift sect-ions in the .xed tube 112, the bracket .185 is positioned well below the pulley 183 so that there is a considerable stretch of cable between them.

To prevent relative rotation of the top post with respect to the intermediate tube 171, a finger 187 is mounted on the intermediate tube 171, above the pulley 183, and rides in the groove 177.

As the intermediate tube 171 of this lift mechanism is raised by the main cable 136, that intermediate section raises the pulley 183, and causes the secondary cable 179 to lift the top post 175 with respect to the intermediate tube 171.

With three sections in the lift columns, three-section ladders are provided. The lower xed section is the same as that in the construction of Figs. 1 to 7, and is xed to the truck or to the xed tube 112 in a position lying to the rear of the lift column. An intermediate ladder section 160 is carried by the intermediate tube 171, its lower end being secured to and supported by the stud 148 and its upper end being held by a bracket 173 on the upper end of the intermediate sec-tion 171. As shown in Fig. 9, the bracket is formed to provide a trackway 191 for the top ladder section 189. The top ladder section is carried by the platform 116, and is received in guiding relationship in the trackway 191, so that it lies against the back side of the intermediate ladder section 160. The upper two ladder sections extend with respect to each other as the upper two lift sections are extended, and are lifted and swung 90 with respect to the bottom ladder section as the intermediate tube 171 is lifted and rotated 90 with respect to the fixed lift tube 112.

With three sections 112, 171, and 175 in each elevator column, a higher extension ofthe platform is possible than with the single-stage lift mechanism of Figs. 1-7. Otherwise the operation of the modified construction is similar to the rst construction shown.

With the platforms in retracted position, they lie sub stantially within the vertically projected area of the truck,

the ladders lie flat against the side of the truck, and the whole assembly is of a height which permits the truck to be driven on the roads in a normal way and with adequate clearance to pass under wires, bridges, trees, etc. Where service work is to be done, the truck is stopped in a suitable position, and the windlass is operated to lift the platforms. As they start to rise, they swing to their transverse positions to form the elongated transverse walkway above the truck, and they can then be raised to the height required for the work. The access ladders rise and swing with the platforms, to provide access at any elevation. The lateral extension of the walkway beyond the sides of the truck permits the servicemen to reach areas spaced from the side of the truck. For example, in painting streetlight mast arms, the supporting poles are frequently positioned a considerable distance from the roadway, yet with the equipment of this invention, the truck may be parked at the edge of the roadway and the whole length of the mast arm, and the top of the pole, may be painted in one setting.

The lift mechanism operates quickly, and the apparatus is easily movable from one setting to another. The poles and mast arms of a series of spaced street lights, for example, can be painted with little effort and time wasted in moving apparatus between poles or from one position to another at any one pole.

I claim'as my invention:

1. Platform apparatus, comprising a generally rectangular platform, a guardrail carried by L-sh'aped supports pivotally mounted at the extreme end of the horizontal leg thereof on the platform on a central longitudinal axis, said rail structure being movable about said axis between a storage position in which the vertical portions of said support depend past one side of the platform and an operative position in which the vertical portions upstand adjacent the opposite side of the platform.

2. Platform lift apparatus, comprising a fixed column sec-tion, an intermediate column section, means to elevate lthe intermediate section, an upper section slidably movable With respect to the intermediate section, and a tension member fixed at one end to the top member, extending over a pulley carried by the intermediate member, and xed at the other end to the xed section, whereby elevation of the intermediate section extends the top section therewith and with respect thereto, and guiding means to hold said sections `against rotation during a major portion of their relative movement and to rotate the upper section with respect to the fixed section during a minor portion of their relative movement, and a platform supported on the upper lift section.

Referencesv Cited in the tile of this patent UNITED STATES PATENTS 1,412,159 Bolte Apr. 1l, 1922 1,638,611 Baldwin Aug. 9, 1927 1,664,613 Royer etal Oct. 4, 1927 1,685,144 Austin Sept. 25, 1928 1,736,419 Smith Nov. 19, 1929 2,196,511 Wagner et al Apr. 9, 1940 2,601,092 Cardiff June 17, 1952 2,614,893` Merrill et al Oct. 21, 1952 2,672,319 Nelson Mar. 16, 1954 FOREIGN PATENTS 470,163 Germany Dec. 20, 1928 

